People have been using drones to smuggle goods for years. Porn, weapons, drugs—god, so many drugs. The tiny whirring machines have proven discreet little contraband-transport contraptions, but one smuggling operation’s astoundingly successful run just got grounded.

From July 2015 through May of this year, a drone gang made at least 49 flights into prisons in England and Scotland, smuggling in weed and mobile phones. But authorities just jailed eight people after cameras set up outside a prison in Worcestershire to capture wildlife caught them in the act, according to the BBC.

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Craig Hickinbottom, a 35-year-old inmate, led the operation from inside prison, the Guardian reports. He was sentenced to seven years and two months for his role. The drone pilot, Mervyn Foster, was sentenced to six years and eight months. In total, Hickinbottom’s team smuggled between £600,000 and £1m of goods into prisons across the UK, authorities said.

To whir in the goods, the smugglers strapped them onto the drones using fishing line and hooks and then flew the clever ‘copters over the prison walls. Inmates would reportedly grab them using broom handles or makeshift hooks.